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Q: My car is showing two trouble codes: P1639 and PO452

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Need to repair the two codes PO452 and P1639 in order to pass emissions

My car has 81000 miles.
My car has an automatic transmission.

Hello. The diagnostic codes you are receiving may be a result of both sensors failing, or a power supply issue. The code P1639 stands for an A/C refrigerant pressure sensor voltage shortage. The second code P0452 stands for the fuel tank pressure sensor voltage shortage. While it’s possible that both sensors can fail at once, it’s also possible the voltage references are being disturbed. You can attempt to replace the fuel pressure sensor and refrigerant pressure sensor and see if the codes go away. You can also trace the voltage with a voltmeter in order to find where the voltage drop occurs.

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